1. Field of the Invention
This invention relates to a testing apparatus for testing a semiconductor device and particularly to a testing apparatus for testing a semiconductor device according to a test program by supplying a test signal to the semiconductor device under test having a plurality of terminals with a power supply system being connected thereto.
2. Description of the Prior Art
FIG. 5 is 1 view showing an example of a conventional testing apparatus for semiconductor device. This testing apparatus comprises a socket 2, a tester 3 and a load board 4. A semiconductor device under test (hereinafter referred to as DUT) is tested by this testing apparatus according to a predetermined test program. The DUT 1 is provided with terminals 1a to 1j, to which an external apparatus is connected. The socket 2 is formed so that the DUT 1 can be removably attached to the socket 2. Terminals 2a to 2j the number of which is equal to the number of the terminals 1a to 1j of the DUT 1 are provided in the socket 2. The terminals 1a to 1j of the DUT 1 put in the socket 2 and the terminals 2a to 2j of the socket 2 have one-to-one relations respectively. The tester 3 forming a main body of the testing apparatus transmits and receives a test signal to and from the DUT 1 and also applies and receives electric power to and from the DUT 1. Pins 3a to 3j for inputting and outputting the test signal and the electric power are provided in the tester 3. For these pins 3a to 3j, so-called "pogo pins" are usually used for the purpose of obtaining good electrical contact. The pogo pins are pins containing a spring, which are retracted when pressed and are returned to their initial state when released. The load board 4 serves to connect the socket 2 and the tester 3. The wiring board 4 is structured so that the test signal and the electric power from the tester 3 may be accurately transmitted to the terminals 2a to 2j of the socket 2.
In the above described testing apparatus, the signal from the tester 3 is applied to the DUT 1 through a path connecting for example a pin 3j, a wire on the wiring board 4, a terminal 2j and a terminal 1j, while the output from the DUT 1 is transmitted to the tester 3 through a path opposite to the above stated path.
FIG. 6 is a connection diagram of the testing apparatus shown in FIG. 5. Referring to FIG. 6, the tester 3 contains a plurality of pin electronics cards as shown by the dotted lines. Each pin electronics card comprises a circuit including various components on a substrate in the form of a card, to which a pin is attached. For example, a driver D, a comparator C and relays R1 and R2 are provided on a substrate. The driver D is interposed in a signal output path and the comparator C is interposed in a signal input path. The relays R1 and R2 serve to connect the driver D and the comparator C with the associated pin respectively. The relays R1 and R2 are turned on and off by control based on the test program. The tester 3 further contains a power source PS and a ground GND. In this example, the power source is connected to the pin 3f and the ground GND is connected to the pin 3e. The ground GND is a power source for applying a ground potential and the power source PS is a power source for applying a potential different from the ground potential. Therefore, the power source PS and the ground GND will be indicated in this specification as a power supply system which includes both the power source PS and the ground GND. The tester 3 further comprises, in addition to the above described components, a storage device for storing the above stated test program, a test signal generator and other components. However, illustration and description of such components will be omitted since they do not have direct relation with this invention.
The wiring board 4 is provided with wires 4a to 4j for electrically connecting the pins 3a to 3j with the terminals 2a to 2j of the socket 2.
Electric power from the power supply system is supplied to the DUT 1 through a path connecting the power source PS, the pin 3f, the wire 4f, the terminal 2f and the terminal 1f, or through a path connecting the ground GND, the pin 3e, the wire 4e, the terminal 2e and the terminal 1e. Generally, those power supply paths are fixedly connected by wires on the wiring board 4.
As described above, the power supply paths are fixed in the conventional testing apparatus. However, the terminals 1e and 1f of the DUT 1 are not always used as power supply terminals and other terminals are sometimes used as power supply terminals. Consequently, since there are various kinds of DUTs 1, it is necessary to change the connection for the power supply path each time a different kind of DUT 1 is used. Thus, such a conventional testing apparatus can not be used widely. In order to solve this problem, it may be considered to use a method in which a plurality of wiring boards 4 having different connections are prepared in advance and a suitable wiring board 4 is selected for testing according to the kind of the DUT 1 concerned. However, such a method is troublesome since it is necessary to change a wiring board each time a different kind of DUT 1 is used. In addition, the testing cost becomes high since a plurality of wiring boards need to be prepared.